Title: Remodeling Interactive Video

Origination

Origination
- Microfracture or microdamage occurs and sensed by osteocytes
- Osteocytes secrete messages to the surface cells
- A circulatory canopy is formed from the lining cells

Osteoclast recruitment
- Osteocytes activate stromal cells to produce M-CSF which stimulates pre-osteoclast differentiation
- Stromal cells divide to produce pre-osteoblasts expressing RANK-L
- Which activate RANK receptors of pre-osteoclasts to activate mature osteoclast development

Osteoclast recruitment

Resorption
- Osteoclasts resorb bone
- At any given site, resorption lasts about 2 weeks
- Programmed osteocyte apoptosis is delayed by estrogen deficiency.

Resorption

Osteoblast recruitment
- Runx2 stimulates stromal cells to differentiate to osteoblasts
- Growth factors, BMPs, and Wnt-signalling play important regulation roles

Osteoblast recruitment

Osteoid formation
- Osteoblasts make layers of osteoid (red)
- Cavity is slowly refilled

Osteoid formation

Minealization
- At 6 um thick, osteoid begins to minearlize (light green)
- Regulated by osteoblasts

Mineralization

Quiescence
- Osteoblasts turn into lining cells or osteocytes
- "Rest" before next remodeling

Quiescence

Mineral Maturation

Mineral maturation
- For months after cavity is filled, mineral crystals are packed closely (dark green)
- Density of new bone increases

Choose the correct statement.

Credits: One Basic Remodeling Unit; by Susan Ott, MD; 1998-2016; source http://courses.washington.edu/bonephys/Gallery/Flashmovies/opmovies.html